Sierra ; Polaris DC04 - RCA - January 14, 2026

Introduction

This document serves as a Root Cause Analysis for the service interruption experienced by Sierra and Polaris customers–hosted in DC04 (Chicago Data Center).

The goal of this document is to share our findings regarding the event, specify the root cause analysis, outline actions to be taken to solve the downtime event, as well as preventive measures Clarivate is taking to avoid similar cases in future.

Event Timeline

Service interruption was experienced by the single-tenant Sierra and Polaris environments hosted in Clarivate’s Data center in Chicago, during the following days:

January 14, 2025, from 01:28 AM until 08:30 AM CST.

During the event, the service was unavailable.

Root Cause Analysis

Clarivate Engineers investigated this event to determine the root cause analysis with the following results:

Three weeks ago an unexpected fault surfaced on a storage device, triggering a defensive read-only state across all data-center applications. Immediate joint analysis with the vendor identified the underlying defect that caused the read-only condition and yielded a recommended remediation. On January 13, early indicators showed the fault was likely to recur, prompting us to schedule the vendor supplied fix as a proactive, preventative measure.

When the solution was finally deployed, it produced a critical failure within the storage device, causing a severe outage that impacted on numerous applications and demanded immediate containment and recovery actions before full service could be reinstated.

Our engineers quickly understood the magnitude of the event and acted with sense of urgency to restore all applications and environments to normal operation.

Some systems did not come up cleanly and required triage, remediation and restore activities with more prolonged downtime on Jan 14thand in some cases Jan 15th.

Technical Action Items and Preventive Measures

Clarivate has taken the following actions and preventive measures to avoid such an occurrence in future:

· We are working closely with the vendor to have full technical analysis of the event, that covers the entire spectrum of the event and have permanent final solutions.

· Refinement of internal procedures and the development of an improved startup procedure to accelerate recovery timelines and ensure a structured return to service.

· Improving the Network and Storage architecture and implementation for Sierra and Polaris environments.

Customer Communication

Innovative is committed to providing customers with prompt and ongoing updates during Cloud events. Ongoing and prompt updates on service interruptions appear in the system status portal at this address:http://status.exlibrisgroup.com/

These updates are automatically sent as emails to registered customers